Android Emulator vs Hercules

Android Emulator simulates Android devices on a computer so developers can test applications across device types and Android API levels without a physical device. It comes with Android Studio and needs no separate installation. Predefined virtual-device profiles cover phones, tablets, Wear OS, Android Automotive OS, and Android TV. An Android Virtual Device sets the Android version and hardware characteristics, and has private storage for user data, SD card data, and cache. The emulator can simulate calls, text messages, locations, network speeds, rotation, hardware sensors, and Google Play Store access. It supports multiple instances, keyboard mapping, gamepads, and root access. The first launch may take about a minute; later launches can use a snapshot and start faster. Supported systems include 64-bit Windows 10 or newer, macOS 12 or newer, Linux, and ChromeOS. The recommended baseline is 16 GB RAM and 16 GB disk space, with higher requirements possible for newer API levels or larger virtual devices. Android Studio on ChromeOS deploys apps only to connected hardware devices.

Hercules is a free, open-source emulator for IBM System/370, ESA/390, and 64-bit z/Architecture mainframes. It lets a PC execute programs designed for those systems and represents mainframe I/O devices with PC resources, including DASD files and local tn3270 sessions. It does not provide an operating system, so users must supply one or run a standalone program. With legally licensed software, it can run z/OS, z/VM, z/VSE, OS/390, VM/ESA, VSE/ESA, and older related IBM operating systems. Features include dynamic reconfiguration, an integrated console, interpretive execution, debugging tools, and snapshots and restore. Guest TCP/IP networking can connect to the host through TUN/TAP and hercifc, and multiple instances can share devices. Hercules is licensed under the Q Public Licence and runs on Linux, macOS, and Windows; the host list also names Solaris and FreeBSD. Documented unsupported areas include ESCON, FICON, PR/SM, coupling links, and several z/Architecture facilities. Its FAQ says it has not claimed production capability and was intended as a system programmer's toy.